1. Field of the Invention
The present invention relates to door systems for railway vehicles and, more particularly, to door systems which provide for boarding from both high and low level platforms.
2. Description of the Prior Art
Railway vehicles are often used on railroad lines having passenger stations equipped with high boarding platforms extending at the vehicle floor level and others with low level boarding platforms extending at or near ground level.
Accordingly, efforts have been made to develop door systems providing for both high and low level access. For instance, U.S. Pat. No. 5,070,794 issued on Dec. 10, 1991 to Kunst et al. discloses a multi-sectioned sliding door assembly for use with a railway vehicle having a stairwell extending downwardly from the floor of the vehicle to a lower boarding level. The sliding door assembly comprises an upper sliding door displaceable to an open position for high level boarding and a lower sliding door disposed immediately below the upper sliding door and displaceable therewith to an open position for low level boarding. The upper sliding door is supported at the top by a sliding connection to a door overhead structure. An upper threshold is secured to an upper outer section of the lower sliding door to be positioned adjacent an elevated platform of a train station. The lower sliding door is connected via a slide assembly to the railway vehicle structure in the region of the upper threshold platform. In addition, the bottom of the lower door panel is guided in a lower threshold. A stairwell platform is hingedly connected to one side of an upper horizontal plane of the stairwell for covering the same during high level boarding.
Although the door assembly of the above mentioned patent is effective for enabling both high and low level boarding operations, it has been found that there is a need for a simpler system which requires fewer adjustments.